Excerpts from the Non-Volatile Memory (NVM) Express (NVMe) over Fabrics (NVMeoF) specification 1.0, section 1.5.6, defines a discovery mechanism that a host may use to determine the NVM subsystems the host may access. A Discovery controller supports minimal functionality and only implements the required features that allow the Discovery Log Page to be retrieved. A Discovery controller does not implement Input/Output (I/O) queues or expose namespaces. A Discovery Service is an NVM subsystem that exposes only Discovery controllers. The method that a host uses to obtain the information necessary to connect to the initial Discovery Service is implementation specific.
The Discovery Log Page provided by a Discovery Controller contains one or more entries. Each entry specifies information necessary for the host to connect to an NVM subsystem via an NVMe Transport. An entry may specify an NVM subsystem that exposes namespaces that the host may access, or a referral to another Discovery Service. The maximum referral depth supported is eight levels.
The Baseboard Management Controller (BMC) has been widely used in servers, PCs, switches and other computer-based products. Generally speaking, the BMC depends on host processor and/or operating systems to initiate and complete the discovery process. In addition, the BMC does not care about what chassis it is in, since its main job is to monitor the health status of the system.
The sensors associated with the BMC measure internal physical variables such as temperature, humidity, power-supply voltage, fan speeds, communications parameters, and operating system (OS) functions. If any of these variables happens to stray outside specified limits, the administrator is notified. That person may then take corrective action by remote control. In some cases, the BMC may take some corrective actions such as increasing fan speeds or rebooting the failed subsystems. The monitored device/system may be power cycled or rebooted remotely, as necessary and/or appropriate. In this way, a single administrator may remotely manage numerous servers and other devices simultaneously, saving on the overall operating cost of the network and helping to ensure its reliability.
A need remains for a way for to reduce the time required for the host to identify all NVM devices in the chassis.